1. Field of the Invention
The present invention relates to a high speed transmission electrical connector, and particularly to such a connector with improved conductive contacts.
2. Description of Prior Art
With the development in computer and communication technologies, high speed transmission electrical connectors, such as Infiniband, backplane, serial ATA and so on, are used more and more by industry business. At the same time, differential signal transmission systems are used for such high speed transmission connectors since they offer signal transmission with relatively low voltage swings and good noise rejection. Thus, a high speed transmission connector commonly comprises a plurality of differential pairs of conductive contacts for transmitting high speed and high frequency differential signals between an electrical component and a circuit board. However, each differential pair has an upper and a lower conductive contacts which are separated from each other, wherein the lower contact is shorter than the upper contact in its whole length, thereby causing electrical skew between the upper and lower contacts and thus resulting in propagation delay. Particularly in high speed systems, the effect of propagation delay is detrimental to signal integrity. On the other hand, the system impedance due to design variation of either the upper or the lower contact of the differential pair must still be maintained for reliable signal transmission.
Accordingly, the present invention is intended to provide a high speed transmission electrical connector having a plurality of differential pairs of conductive contacts which can meet the electrical skew and impedance control requirements, simultaneously.
A main object of the present invention is to provide a high speed transmission electrical connector having a plurality of differential pairs of signal contacts which can meet not only electrical skew but also impedance control requirements.
An electrical connector in accordance with the present invention is used for transmitting high speed signals between an electrical component and a circuit board. The electrical connector comprises a dielectric body defining a plurality of passageways, a plurality of signal contact units and grounding contacts alternatively retained in the passageways. Each signal contact unit has a differential pair of upper and lower contacts separated from each other, wherein the lower contact is shorter than the upper contact in whole length thereof. Each of the upper and lower contacts comprises a retaining body, a resilient beam to be mated with the electrical connector and a soldering portion to be soldered to the circuit board extending from opposite ends of the retaining body, respectively. The retaining body of the lower contact defines a cutout like an inverted funnel in cross section at an upper side thereof adjacent to the upper contact.